perf(autoloader): Drop legacy class autoloader

[ChristophWurst]

• Resolves: n/a

Summary

The documentation says apps should use PSR-4 to get their classes loaded. The legacy PSR-0 is still in place and has a negative impact on performance.

1. PSR-4 autoloading was introduced in PSR-4 for apps owncloud/core#24386
2. App autoloader support was added in Allow apps to have their own autoloader #6853
3. Our documentation says app should use PSR-4 https://docs.nextcloud.com/server/latest/developer_manual/digging_deeper/classloader.html. PSR-0 (legacy) is not even mentioned.

PSR-0 was deprecated in 2014: https://www.php-fig.org/psr/psr-0/. Our docs also list it as deprecated: https://docs.nextcloud.com/server/latest/developer_manual/digging_deeper/psr.html#psr-0-autoloading

This is a hard breaking change for the apps that have not yet been upgraded to PSR-4. Therefore I would suggest to warn about this in the 26 upgrade docs and drop the loader only with Nextcloud 27 or later. @AndyScherzinger @PVince81 your call.

Benchmarks

time for i in `seq 1 100`; do php occ; done

Before

real 0m53,323s
user 0m46,178s
sys 0m6,851s

After

real 0m49,161s
user 0m42,581s
sys 0m6,555s

^ that is 7.8% speedup for a generic Nextcloud process

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
  • feat(devmanual): Document PSR-0 autoloader removal documentation#10231
• Backports requested where applicable (ex: critical bugfixes)

[PVince81]

👍 cool!

[PVince81]

it's still early enough. if we kill this for NC 26 we then need to communicate this as soon as possible on the forum with instructions how to migrate

a question also is how difficult it is, whether it's just an hour of work or requires rewriting of things

[ChristophWurst]

a question also is how difficult it is, whether it's just an hour of work or requires rewriting of things

It's about renaming php class files. The effort depends on the number of files that need a rename.

[come-nc]

Is it faster because it’s faster or because some classes are not loaded anymore?
How certain are we this is not used in core?

[ChristophWurst]

Is it faster because it’s faster or because some classes are not loaded anymore?
How certain are we this is not used in core?

That is an absolutely fair point

But CI is quite happy and I believe we migrated all PSR0 files to PSR4 at some point. It was a series of PRs by @nickvergessen and @rullzer.

[nickvergessen]

How certain are we this is not used in core?

I guess there is only one way to find out: 🍿
But yeah, we moved almost everything back then I guess. I would say check back on files_sharing and files_external, that could be the non-default points still using old tech as automigration failed, but I think all was done back then

[AndyScherzinger]

This is a hard breaking change for the apps that have not yet been upgraded to PSR-4. Therefore I would suggest to warn about this in the 26 upgrade docs and drop the loader only with Nextcloud 27 or later.

As suggested by Christoph, let's warn with 26 and drop on master after release of v26 that should give everyone enough time to upgrade or fix respectively, including us on core/server if needed.

[ChristophWurst]

let's warn with 26

PR at nextcloud/documentation#9553

[ChristophWurst]

It's showtime

[szaimen]

/rebase

[DaphneMuller]

Hello!
Thank you for your work on this! I noticed that your PR still has the label 'documentation'. I'm not sure if you already had a look at the documentation for your PR, but at Nextcloud we strive to document changes that affect other app developers or other admins before the release takes place, and I'm pinging you with the hope to get this done.

Are you familiar with our documentation process already?
Changes that affect app developers should be documented here:
https://docs.nextcloud.com/server/27/developer_manual/app_publishing_maintenance/app_upgrade_guide/upgrade_to_27.html

Changes that affect administrators should be documented here:
https://docs.nextcloud.com/server/latest/admin_manual/release_notes/upgrade_to_27.html

While I understand sometimes it's handy to merge fast to get your changes in, it would be great if next time you could try to add the documentation before merging. You can find more information on that here:
https://docs.nextcloud.com/server/27/developer_manual/prologue/compatibility_app_ecosystem.html#documentation-procedures-of-changes-that-affect-app-developers

If all your documentation efforts are done, please remove the label 'documentation' and check the checkbox in your opening note and I'll stop bugging you :)

Many thanks in advance and thanks again for your work!

[nickvergessen]

Documentation is in nextcloud/documentation#10231